Contagion
by MDB2005
Summary: Zombie AU, Johnlock, Slash (M/M), Explicit. When a virus spreads causing an epidemic, London falls. Can the great Sherlock Holmes and Dr. Watson stop it before it is too late? Warnings for violence and dark themes. No Beta, not brit picked, please excuse any errors. Disclaimer: I own no character rights and make no profit. Reviews welcome.
1. Chapter 1

Contagion

Chapter 1

Yea, though I Walk through the Valley of Death

London

Present Day

John Watson

John never thought that there would come a day when he would miss the afghan desert, but now, looking back, the war had been child's play. He wondered, not for the first time since this whole thing began, if he would have been better off bleeding out in the desert during his last tour of duty. How had it gotten to this point? It seemed like a lifetime ago. Another lifetime. Another reality. How had he gone from a wounded solider in Afghanistan, to an A&E physician working in London to supplement his army pension and finally, to one of the few survivors left in London?

John's head snapped around as the sound of a lone howl broke the silence in the distance. He ducked low behind an empty skip before cautiously peering out on the lookout for any type of movement. Anything could draw them out. John took a deep breath and forced himself to stay calm. Most animals were immune and were therefore useless as carriers, but infected were opportunistic eaters. John's stomach cramped as he waited for them to come searching for the source of the noise. The city appeared abandoned, nothing left but death and decay, but John knew better. It was a concrete jungle and some things lay hidden just beneath the surface, the things that nightmares were made of. Then, moments later, another break in the silence came in the form of a shot. John looked around wildly breathing in deeply as his nostrils flared. His tongue slipped out from between his lips and tasted the air. Nothing, nothing close anyway. John continued to scan his surroundings finding no signs of life. Perhaps he had imagined it. Sometimes he heard things that he couldn't explain. Was he going mad? Sometimes he felt like it. Prolonged isolation could do that to a man. Make him question his own sanity, but John didn't have the luxury of self-doubt anymore. Treat everything as reality until proven otherwise; it was that thought which had kept him alive more than once. John looked around once again, his eyes skimming the deserted streets littered with dead bodies.

John stifled a gag as the smell of rotting flesh surrounded him. John always considered himself to have a strong stomach, something that was practically a requirement in the medical field, but ever since he had been exposed to the virus, his sense of smell wasn't the same. John wasn't the same. His senses were more acute, particularly his sense of smell. John couldn't bring himself to complain though. After all, it was his newly acquired acute senses that had saved him more than once. Once he had learned to properly harness them, it had taken time for John to pinpoint the meaning of all the significant smells and to learn to differentiate between them. John grit his teeth and forced himself to breathe in deeply and catalogue it. He now knew that the infected possessed a scent signature that he could detect at close distances. Once he was sure that there were none in the immediate area, he breathed through his mouth in order to minimize exposure to the stench of death and decay.

All of his senses were now more acute. Why remained a mystery; perhaps it was a side effect of the exposure and his body's immune response to fight off the virus. There were other changes as well. When John had first awoken from the coma, his muscles had atrophied significantly leaving him weak and vulnerable. He had been lucky to make his way out of the hospital and find shelter before nightfall. Then something strange began to happen. What should have taken months of intense therapy to regain his strength had only taken a couple of weeks. John's body recovered at an unnatural pace. He was now stronger than before he was exposed, gaining both strength and muscle mass. But along with increased strength and sharpened senses other less desirable traits had also appeared. Mood swings and aggressive tendencies, which were brought on by what John guessed were surges in testosterone. It left John confused and more than a bit concerned and afraid. Was this a new mutation of the original virus or simply a by-product of immunity?

Immune, John was one if the few people who were naturally immune. John didn't know whether to consider that to be a blessing or a curse at this point. London had fallen. John moved quickly back to his temporary home eager to escape before the infected hunted down whatever poor animal had produced that mournful howl. John rubbed the base of his neck trying to soothe the near constant ache that had settled there. He winced as he massaged swollen and tender lymph nodes and large nodule at the base of his neck, which were still swollen over a month after his initial exposure to the virus. The cervical nodes were enlarged on both sides of his neck, but more concerning to John, was the large nodule at the base of his neck which had appeared after his exposure. It wasn't a lymph node, the placement was wrong. It was yet another mysterious change within his changing body that he couldn't explain.

John thought briefly of Harry and what had become of her. He had made his way to her London flat a few days after he had awoken. It had been empty, and clearly looted. John hadn't found any trace of his sister, but still held out hope that she had gotten out of the city before it had fallen. London was a wasteland now, a pale shadow of its former glory. It had become a breeding ground for infected. The virus had been merciless. As John made his way back to shelter he looked around the streets for anything of value that was worth scavenging. He was careful to stayed hidden in the side streets and alleys, always mindful that there were infected looking for an easy mark.

John's hand moved to the small of his back tracing the outline of his browning. He was running low on ammunition and he did not want to use it unless left with no other alternative. His immunity gave him more leeway than most. He could risk exposure without fear of infection, but just because he couldn't catch the virus didn't mean that he couldn't be killed. The infected would eat anything, even each other. The virus affected the nervous, endocrine as well as the musculoskeletal systems. It caused brain damage, shutting down the frontal and temporal lobes as well as portions of the limbic system, leaving the parietal lobes and cerebellum damaged and leaving only the brainstem fully intact. The virus also wreaked havoc on the adrenal glands and eventually led to renal failure and death. The virus killed the host, but it was a slow death and the infected were able to cause massive amounts of damage until their bodies finally shut down. They couldn't feel pain and were very difficult to kill. Their bodies were capable of producing massive amounts of adrenaline giving them almost inhuman strength.

John licked his dry lips as he mentally reviewed the few facts that he had been able to piece together. It had spread like wildfire. It was a pandemic the likes of which the world had never seen. The NHS and WHO had been powerless to stop it. It had mutated quickly, so quickly that a viable vaccine had been more of a dream than a reality. The infected lay dead in the street. Immunity was rare and as a consequence, nearly everyone exposed to the virus became infected and died eventually, but not before they turned into something inhuman; something feral and bloodthirsty. John shuddered as he recalled the first time he seen one fully turned. The day he was first exposed. It was in the ICU at St. Bart's, ironically. The patient had initially come in for a bite wound that had become infected. Looking back, they should have questioned him. If they had, they may have suspected something and, at the very least, had the man quarantined, but they treated it as routine. The patient had been admitted to the medical ward for IV antibiotics. When the condition worsened to fully blown septic shock, the patient had been transferred to the ICU and put on a ventilator. It was then that it had happened. The PA system had requested a code team and security. John had been in the covering the A&E at the time, so it was he that had responded to the code.

What he saw when he had gotten there had stolen his breath. John had seen death in different forms, both natural secondary to disease and man-made as a result of war, but he had never seen anything like what he had seen that day. The patient had been bucking against the restraints, drooling with bloodshot, dilated eyes. He was completely feral. The sedation had no effect and soon the patient had broken free. With an inhuman scream, the patient had lunged at the nurse taking a bite out of her arm. They had no choice but to killed him, but not before the patient had bitten everyone in the room, John included. They hadn't known what it had become at the time and had no idea what was coming. John looked down at his left forearm. The silver scar was a near perfect dental impression of the patient's teeth. It served as a constant reminder of that life-changing day.

He hadn't been the same since that bite. John had gotten deathly ill as his body fought the virus. His immunity eventually won out. He was one of the lucky ones. Even the rare individuals who had a natural immunity to the virus were not completely safe. Fighting the virus required the body to mount a massive immune response and those whose bodies were not strong enough died fighting the infection. At first, John had thought that he would be one of them. The fever had raged unabated and no drugs could help to fight the infection. He his organs began to shut down and he had slipped into a coma. The virus had nearly taken his life. When his body finally fought it off, he had awakened from the coma to find the hospital abandoned.

John took a deep breath as he recalled the panic that he had felt as he roamed the halls of St. Bart's finding nothing but dead bodies in various stages of decay. The hospital had been boarded up, it now resembled a prison, designed to keep things in rather than keep them out. To this day, John wasn't sure how long he had been comatose, but it must have been long enough for the city to have fallen prey to the virus. Looking back, it was a miracle he had survived those first few days. He had been comatose as the virus had spread and remained blissfully unaware of what was awaiting him when he awoke. John's medical and military training had been instrumental in saving him. He had been forced to learn the hard way. He had been able to gather a few facts from the notices posted throughout St. Bart's, but they had only contained minimal information regarding transmission. Blood and bodily fluids, most often through a bite wound as well as signs and symptoms of infection in regards to the physical and neurological deterioration seen as the virus progressed. Nothing was mentioned about the infected weaknesses or any type behavioral patterns.

John had learned that through trial and error. Fully turned infected were the most dangerous; feral scavengers without higher brain function or pain response, but deadly and nearly impossible to kill. The freshly infected could be deceiving, there was a window period between initial exposure to fully turned infected of about a week where the infected individual appeared normal except for the wound which served as the point of entry for the virus which would not heal. Though they were not feral, they were still contagious and were carriers of the virus, ticking time bombs, so to speak. He had been surviving by scavenging and moving constantly around the city, never staying in one place for long. It had been just over a month since he had awoken from his coma and he had never felt more alone. He had yet to find anyone who was not infected.


	2. Chapter 2

Chapter 2

Needs Must

Anthea

Anthea tied her long chestnut hair into a tight bun making sure that there were not any loose strands. She then loaded the magazine with practiced ease and slipped the weapon into her shoulder holster. She adjusted the ankle blade and tightened her bulletproof vest before covering it with a jacket. She sprayed the military strength scent blocker over her body and finally put on her night vision goggles. She was going hunting for ghosts. She paused a moment to recall how she had gotten here. The virus was spreading despite quarantines and it was becoming apparent that the only way to stop it in its track was a vaccine. Even before the outbreak, the NHS had been underfunded and overwhelmed. The virus had quickly overwhelmed an already struggling system and the NHS had been one of the first agencies to collapse. The hospitals were abandoned and bordered up serving as unmanned prisons to those infected that were left inside before turning feral. Not only had their hospital's failed, but the nation's healthcare workers had dwindled down to frighteningly low numbers. Many had been infected attempting to treat the sick and the few that remained had fled. It made the possibility of a vaccine even bleaker. Anthea did not hold false hope, but she refused to lay idle and wait for death. She would die fighting until her last breath.

She had lost contact with Mycroft during the fall but knew that deep down that he was still alive. She had fled London with other high-level officials planning to return once a vaccine was viable. She had left with the understanding that Mycroft Holmes would follow. "I won't leave without him." He had insisted. Sherlock Holmes, the man was Mycroft's one true weakness. Her employer was a private man and she knew little about his past, particularly his childhood and strange relationship with his younger sibling. Even after nearly ten years under his direct employ, much of his life remained a mystery to her. She knew the basics; impeccable education, matriculating from Harrow, then Oxford with honors. He began his career at MI5 as a field agent and though he lamented legwork, he quickly developed an impressive skill set and quickly worked his way up through SIS and then the home office. His intelligence was legendary as was his ambition. He was unrelenting in his pursuit of perfection. It was this drive that had led to him becoming one of the most powerful men in all of Great Britain. He could be cold and calculating, so much so that many called him the iceman, but Anthea knew better. Though Mycroft often claimed that caring is not an advantage, he was not completely immune to sentiment. His brother, Sherlock Holmes, was the one person that Mycroft feared losing. Their relationship was difficult to describe, for all the animosity, their was also a begrudging respect and concern between them hinting at something much deeper than first appeared on the surface. Anthea knew better than to question it. If her employer did not freely give information, then it was considered off limits unless otherwise specified.

She picked up her blackberry and dialed. While a team could not be spared for this mission, Anthea was not suicidal and knew that she needed backup if she was going to have a shot in hell at a rescue mission. At this point in time, her choices were slim for many had perished during the fall. There were few left who were loyal enough to consider what could very well prove to be a suicide mission. The rough voice of DI Lestrade greeted her. "Lestrade."

"Detective, I am calling on behalf of Mycroft Holmes." After great deal of curing followed by rebukes, she had finally persuaded the detective to listen. Once he heard her plea, he agreed to accompany her on her extraction mission. Anthea rung off and sighed, wondering, not for the first time, what would become of humanity.


	3. Chapter 3

Chapter 3

The Path to Paradise begins in Hell

Sherlock

"Oh Sherlock, what have you done?" Mycroft murmured looking horrified as he spotted the bite wound, which was still bleeding sluggishly on Sherlock's left hand. Toby whined pitifully sensing Mycroft's distress. The bloodhound paced anxiously back and forth between them, his muzzle stained with dirt and blood. Sherlock had the hound to thank for his life. It was Toby that had allowed him to escape, but not before being bitten. Mycroft's complexion became even paler as his knuckles turned white as he gripped the handle of his umbrella. His hands trembled and his breath quickened. "How?" He asked in a voice that shook with emotion. Sherlock felt a flash of surprise at Mycroft's obvious show of sentiment. It was quickly followed by shame at his own arrogance.

He had not only put himself at risk, but his brother as well. Mycroft had warned him not to go out alone. _You need someone to watch your back. All it takes is one slip._ He had warned Sherlock when they had settled into Baker's Street. Though Sherlock loathed to admit it, Mycroft had been right. He would now pay for Sherlock's mistake. Though their relationship was still far from perfect, the recent events had brought them closer than they had been since Sherlock was a very young child. Sherlock bit his lip for once at a loss for words. It was over for him; he'd been exposed and was now infected. He shouldn't even have come back to Baker's Street. It seemed as though his risk taking had finally caught up with him. He had been searching for immune survivors, but his search had only led to him being bitten.

There were few physicians left in London and of the few that remained, none were immune. Molly Hooper was one of those few who had chosen to stay. She was working on a vaccine, but she needed someone with immunity in order to move forward. Sherlock had been searching for weeks, but had no luck until today. He had been so close. The blonde man that he had been trailing had so far remained elusive. He never stayed in one place and was constantly on the move and careful never to leave anything behind that the infected may find. He was good and was working alone as far as Sherlock could tell. It led him to deduce that the man had a military background. Civilians rarely demonstrated that level of survival skill without special training. Sherlock had nearly given up, but finally the man left a clue, a small piece of jumper. The small piece of fabric had gotten caught on the jagged end of a skip and torn away from the rest of the clothing. It had been enough for Toby to catch a scent and start tracking.

Sherlock had been so focused on the hound as they drew ever closer to their target that he failed to notice his surroundings. The group of infected gathered and quickly surrounded them. Sherlock had reached for the rifle, but he wasn't fast enough. Before he could shoot, one of the infected tackled him to the ground. Sherlock had managed to ram the butt of the rifle into its head, throwing it off balance. Before he could get up and aim, another was on top of him. It bit his hand before he could pull the trigger. Toby, who had been attempting to hold the group off, let out a mournful howl in response to Sherlock's pained shout. It was almost as if the animal knew what was to come. Sherlock had gotten a clean shot, careful to aim for the head. After taking one out, they ran. Sherlock had debated whether to go back to Baker's Street at all. He always hated goodbyes, but he knew that Mycroft would come looking. For all of their issues, Sherlock did not want his brother's death on his conscience. He had already failed so many. His eyes drifted to the mantle and settled on the urn. It contained Mrs. Hudson's ashes. He had been too late to save her. She had become another victim of the infected. So few remained. Lestrade had fled, but Sherlock knew that unless the virus was contained, then it would all be for not. It would spread, and eventually take all of mankind with it. It was why he had been reckless. Desperation.

"I'm sorry, I'll go. I just wanted to say goodbye." Sherlock whispered. "I thought we were on to something…there was a blonde man, immune, that I was tracking, but he slipped away and I was ambushed." Sherlock looked down at Toby and gave him a scratch behind the ear. He had been a good dog. Sherlock would miss him. Luckily, the virus did not affect canines. Mycroft would not be forced to put him down. "Take it, there are still three bullets left." Sherlock insisted as he handed over the antique hunting rifle, which had belonged to their grandfather, to his brother. Sherlock wouldn't need it anymore. His uninjured hand slipped into his pocket and gripped the pill bottle. He and Mycroft each carried one as a last resort. Cyanide. Death would at least be quick.

Mycroft shook his head. "There's still a chance that you could be immune." He reasoned unwilling to take the gun. "Brother, stay, wait it out. I'll finish it if you turn." He promised looking sicken at the thought but determined. Sherlock sighed and closed his eyes as he calculated the odds. Not good. The risk was too great. He would not endanger Mycroft anymore than he already had.

"No, Myc. I have to go. I've got two weeks at best. If by some miracle I am immune, then I promise that I'll come back, but I can't risk staying." Sherlock insisted shoving the gun into Mycroft's hands.

"Your loss would break my heart," Mycroft confessed leaving Sherlock speechless. His eyes were glassy with unshed tears and Sherlock felt his guilt double and his chest tightened even further with regret.

"Myc…what the hell am I supposed to say to that? I can't risk hurting you." Sherlock replied in a pained voice wroth with sadness. "Brother, please, don't make this harder than it is. I'm sorry…for everything, the drugs, the quarrels, and the feuding. I wanted to make it up to you, but now I'll never have the chance. Je t'aime, mon frère" Sherlock couldn't go on without his voice breaking. Mycroft put the rifle down, leaning it against the wall looking at Sherlock desperately.

Mycroft paused for a moment clearing his throat and wiping his eyes and then pleaded in a hoarse voice taking a few steps closer and taking Sherlock's hand giving it a gentle squeeze. The show of affection was so out of character for his brother that it was a bit unnerving. "Will…" Mycroft choked out. "Please, stay." Mycroft seemed to be breaking every one of his tenets. Sherlock could clearly recall Mycroft saying to him after their father's funeral. "All lives end. All hearts are broken. Caring is not an advantage."

Sherlock shut his eyes and took a steadying breath. He hadn't been called by his proper name since before Mycroft had been sent off to boarding school when Sherlock was six. For a moment, it reminded Sherlock of how close they had been as young children making the goodbye even more painful. Sherlock shook his head. He couldn't stay, it was simply too dangerous.

Mycroft looked shattered and Sherlock could no longer stand to see it. He looked away unable to meet his brother's tortured gaze. "Take Toby, I'll sleep easier knowing that he's with you. If the worst case comes to pass and you perish…he'll find his way back to Baker's Street. He always does." Mycroft requested softly. Sherlock nodded stiffly afraid to say anything else as he attempted to swallow passed the lump in his throat. He whistled sharply and Toby heeled following him out the door.


	4. Chapter 4

Chapter 4

Nothing Lasts Forever

Mycroft

Mycroft released a shuddering sigh as his eyes slipped closed. His brother had been bitten. It was more than he could take. Though Sherlock would never believe it, Mycroft loved him dearly. He always had. Mycroft could still clearly remember his horror the night that he pulled his brother from the flophouse; the filth, air of desperation amongst the drug addled drifters. Discovering his brother in their company had been a shock that he was not prepared for. Mycroft had been at university at the time and Sherlock had only been a teenager. He should have suspected something was seriously wrong when he received a call from his mother, who had not spoken directly to him since the age of thirteen. She had called hysterical claiming that Sherlock had run off. It had taken Mycroft nearly a week to find his brother who had been high and filthy, talking nonsense and fighting Mycroft the entire time. When Mycroft had demanded to know why he had done it, Sherlock had simply replied. "To forget." The look in his eyes spoke volumes and Mycroft knew then that he had failed and things would never be the same between them. Sherlock would never forgive him for leaving.

They had been so close when they were young despite the 7-year age difference. Mycroft could remember holding him as a newborn and falling in love with the babe. Mycroft had taken one look at his angelic face and vowed to always protect him. Yet, despite his promise, had failed time and time again, first from their father, then from the drugs, and finally from the infected. The last being his greatest failure for there would be no fixing this. Bitten, infected, as good as dead. They had a difficult relationship, anyone could see that, but that hadn't always been the case.

When he was young, Mycroft had been home schooled with private tutors giving him the luxury of staying home and allowing their fraternal bond to grow. Mycroft had indulged his brother. He could still clearly remember dressing up as a pirate at his three-year-old brother's request. While at the age of ten, feeling much too old for such fancy. He engaged in play sword fighting atop a mound of cushions assembled into something vaguely resembling a pirate ship. The toddler had been so happy that Mycroft had forgotten his reservations. They had shared more than children's games. Mycroft was precocious as was his younger sibling. Mummy studied music at university before she met and married their father. She had taught both of them to play instruments. Mycroft had learned piano, while Sherlock learned violin. They would often practice together engaging in many classical duets from Mozart, to Beethoven, and Bach, just to name a few.

They had grown up in Musgrove Manor, the large property allowed for exploring. Mycroft sighed as he recalled the sounds of the horses' knickers in the stables and the smell of hay as well as the feel of the horses' stride as they moved effortlessly as one from walk to canter to gallop. Mycroft had adored riding. Sherlock had been skittish around the horses, but the bees had fascinated him. The hives were always a mass of activity with the gentle buzzing of bees in the background. Mycroft had been allergic to bee stings and therefore had to keep at a safe distance much to his brother's disappointment. Summers were spent in France with their beloved grand-mere. When Mycroft had been admitted to Harrow at the age of 13, it had all started to change. His 6-year-old brother had been devastated. Mycroft painfully recalled how terribly Sherlock had taken the news the day that Mycroft had finally found the courage to tell him.

The day had started so well. Mycroft had picked the puppy for his brother hoping that the small pup would help ease his brother's loneliness in his absence. His brother squealed in delight as the Irish setter pup wiggled in his lap jumping up and licking his face. "I'm calling him Redbeard!" His brother proclaimed joyfully with a look in Mycroft's direction. "Merci, mon frère." Mycroft smiled feeling his heart lighten a bit in the face of such happiness.

"You are most welcome, Will." Mycroft had then taken a deep breath and continued. "Will…I'm afraid that I will be leaving for Harrow in the fall. It is a boarding school, one of the best in England." Mycroft explained as his brother's face moved through a range of expressions first disbelief, then sadness, and finally settling on anger.

"You can't leave! Simply refuse!" His brother insisted looking at Mycroft with hurt in his eyes. Mycroft wanted to stay, if only to protect his brother, but that was easier said than done.

The Holmes family came from a long line of aristocrats; there were a number of Lords and nobles in the family with numerous ties to the crown. Their Father was a diplomat as was his father before him. Mycroft knew that he would be destined for some type of government work as well. Traditions, as well as appearances, were of the upmost importance to the Holmes line it seemed. Mycroft had figured this out quickly. At the age of thirteen, he was already well versed in the elite's hierarchy. Mycroft shuddered as he thought of their Father. Even at the age of thirteen, the man still terrified him. He still couldn't understand how Mummy could love him, but there were a number of things that he didn't understand.

During his early childhood, before Sherlock was born, his father had been an apparition, coming and going mysteriously. He could remember the words the staff had used to describe him when he was not in residence. Paradoxical in nature, one moment: aloof, cold, detached, and yet, in the next breath: unstable, cruel, mercurial-akin to a volcano, seemingly sedate and unfaltering, yet capable of unexpected explosions and untold destruction without warning. He had tried his upmost to avoid the man, often spending his days practicing piano in the music room or with his head buried in a book in the library or in the stables tending to the horses. But at night, there was no place to hide and his father often appeared in the darkness smelling of brandy and cigar smoke. Mycroft could not suppress a shudder as the memory of his father's hand ghosting over him made his skin crawl. The visits slowed as Mycroft grew older and had finally stopped all together once Mycroft began to enter puberty. Mycroft had finally told his mother fearing that his father may turn his attentions to Sherlock.

He expected that his mother would be upset, but what had taken place had shocked him to his very core. She had called him a liar and slapped him. He winched as he remembered the sting of the slap as it had turned his head, but the sting of betrayal had been far worse. Mycroft had considered calling the authorities, but if his own mother did not believe him, then neither would they. He had no proof, only his word against his father's. The pop of a log in the hearth pulled him from his thoughts and he looked around the empty flat unsure of where to go from here.


	5. Chapter 5

Chapter 5

No Where Left to Hide

Greg Lestrade

Greg couldn't believe that he was actually going back to ground zero. London had been the first to fall. The city had been quarantined, and while it had helped to slow the spread of the virus, it had not stopped it completely. The virus had continued to spread outside the city and it had yet to be contained. Greg hit the accelerator and his knuckles tightened on the steering wheel as images of his soon to be ex wife and their children lying dead flashed through his mind. They were eaten half alive by a mob of infected while Greg had been out on patrol. Even with the cheating and impending divorce, Greg was still grief stricken. It was a terrible way to die and he wouldn't wish it on his worst enemy and seeing his babies torn apart was more than he could bear. Bloody hell. That had been his breaking point. M25 was deserted.

Greg had been running and fighting for their children. Now that they were gone, Greg was a man with nothing to lose. He wanted to track down Sherlock Holmes and the opportunity had just fallen into his lap. A phone call from Mycroft Holmes personal assistant had come out of the blue asking for his assistance locating Mycroft and by extension, Sherlock. The great detective may be able to find a solution to all of this where everyone else couldn't. He knew it was a suicide mission, but he could admit that he had a bit of a death wish. There were others he still wondered about. Molly Hooper and Mycroft Holmes were the first were that came to mind. Greg now had his answer in regards to Mycroft's whereabouts, the man was evidently hidden somewhere in the bowels of London, likely with Sherlock.

Once London had fallen, marshal law had reigned. While the Met still operated, it wasn't in the traditional sense. They acted as intermediaries and helped with quarantines and evacuations. Vigilante justice ruled. It had become the Wild West and Greg was heading straight into the heart of it. Greg sighed as recalled the screaming match that he had with Sally Donovan when he told her of his plan. "Are you bloody mad?" She exclaimed. "You're signing your death warrant. London's fallen. There nothing left there but death. Even if by some miracle the Freak's still alive in that hellhole, you'll never find him. I won't let you do it Greg."

"It's not your call, Sally. I'm a grown man and I don't need to ask permission. I was simply giving you a heads up as a courtesy. I'm going whether you approve or not." Greg had insisted as he hastily packed his duffle bag. He threw his glock into his shoulder holster and tucked the knife into his belt. Greg could understand her frustration, especially since he hadn't told her that he would have backup once her met Anthea, but it truly was his decision alone.

"You're willing to die hunting for that psychopath?" Sally asked in disbelief. Greg grit his teeth and answered in an even voice.

"Sherlock Holmes is a great man and one day he might even be a good one." Greg had turned away before she could say anything further. It wasn't the way he had wanted to leave things. He and Sally had worked together for a long time and despite her animosity towards Sherlock, Greg did respect her. But this time she had gone too far. Greg was going whether she wanted him to or not.


	6. Chapter 6

Chapter 6

Into the Inferno

Sherlock

"What's going to kill you?" Molly's voice echoed in his head. Sherlock recalled his reply.

"Human error." That had certainly proven to be true. Sherlock looked down at Toby who trotted along beside him. He was at a crossroads. He could hole up and wait to die or he could continue tracking the immune man. Sherlock considered his options. He was a dead man walking and literally had nothing to lose. If he could locate the immune man, then perhaps he could convince him to volunteer in the vaccine study. It was worth a try. Sherlock would have to be quick though. He only had a small window before he became completely feral. His hand slipped into his pocket and clutched the bottle of cyanide.

Sherlock snapped his fingers bringing Toby's attention to him and uttered the command "track" in a low voice. The hound did as ordered and began to sniff the ground looking to pick of the trail of the immune man. Sherlock could only hope that he would be successful. He had given the rifle to Mycroft and his only defense was a small blade. Sherlock stifled a chuckle recalling that he had already been bitten and exposed and it didn't really matter; nothing would save him. But perhaps, he could find the key to saving the rest of humanity.

They moved quickly attempting to stay in the shadows. London, the city that Sherlock loved, was no longer recognizable. The silence was deafening. All the life had vanished. There were no cars, pedestrians, the storefronts were boarded up and what hadn't been locked down had been looted. Windows were broken and even the pigeons were gone. The smell, however, remained. The stench of death was pervasive. Toby whined softly to grab Sherlock's attention. He had worked diligently with the hound to break the habit of howling when a trail ran hot. The last time that Sherlock had heard the dog's mournful howl was the night that he had been bitten. Toby started running and Sherlock followed. "Good boy, find him."

They ran down an alleyway coming to a stop when they reached a steel gate about 3 meters tall. It was lined in with spikes at the top making it very difficult to scale. Sherlock looked down at Toby trying to decide the best way of getting both himself and the hound over the bloody gate. There would be no easy way as the dog was easily 45 kg. Sherlock lifted Toby with a grunt and put the dog over his shoulder. Toby panted heavily and Sherlock could feel his hot breath on the back oh his neck. His hind legs dangled precariously across his chest while his forelegs dug into his back as the dog sought for leverage. Sherlock groaned as he unsteadily climbed the gate. He was able to make it to the top of the steel, but as he hoisted his leg over the top Toby panicked and shifted his considerable weight causing Sherlock to lose his balance. Toby managed to land on his feet with a yip. Sherlock was not so lucky. He landed hard rolling his ankle before falling hard on his side. He groaned in pain as he felt the bones in his right ankle and elbow give way as he landed on the concrete. Sherlock sat up and looked around hoping that he had not attracted attention. Toby whined softly giving his belstaff a tug. Sherlock hissed in pain as he tried to stand. He managed a to get himself upright and stood on one foot unable to bare weight on his broken ankle. It was painful and swelling rapidly. Sherlock managed to hobble along hopping slightly before once again losing his balance and falling flat on his rear. "Bloody hell." Sherlock murmured under his breath in frustration. He wouldn't get far, not in this condition. Toby looked back trotting back to Sherlock with a whine then proceeding to tug on right sleeve jostling his injured arm causing Sherlock to yelp in pain.

Sherlock grit his teeth. This was it. It would all be for nothing. He was a sitting duck. Sherlock ground out the command once again willing Toby to listen. Perhaps Sherlock could persuade the man to volunteer. Assuming that Toby could track the man and lead him back to Sherlock before the infected found him lying helpless. "Go! Toby, track." The dog turned away and began to sniff limping and lifting one paw and Sherlock felt his hopes rise as he watched the hound pick up the trail. Before he could breathe a sigh of relief, however, his heart began to race as the sound of a guttural groan filled the air. Sherlock's eye's widened in panic as he caught sight of an infected moving towards him. He pulled the blade from his belstaff and waited. Toby's head snapped up and a growl erupted from the hound's throat as his heckles rose. The dog leapt on the infected knocking it off balance. Toby went right for the throat. The infected bucked and scratched and kicked but could not break the hound's iron grip. Toby tightened his hold and shook his head. Sherlock heard the tell tale snap of the spinal chord and the infected lay still. It was one of the few ways of killing them, decapitation. "Good boy! Track." Sherlock commanded once again gripping the pill bottle as he watched Toby disappear into the darkness. It would be a race against time.


	7. Chapter 7

Chapter 7

Chasing Shadows

John

John startled awake with a flail. Darkness greeted him. He inhaled deeply searching for the ominous smell of the infected. He relaxed slightly when he sensed nothing. What had woken him? A dream? John had been plagued by nightmares since his discharge from Afghanistan. The dreams had changed from the sounds of explosions from drones and RPG's and the cloaking heat of the arid desert to London's abandoned streets littered with the dead and the stifling smell of death and decay and the hoarse moans and guttural grunts of the infected. Just as John started to drift back under, a soft whine followed by the sound of scratching at the door broke the silence. What the bloody hell? John pulled his browning from under his pillow and moved quietly to the door. The whining increased in volume followed by panting and soft scratching. John scented the air as he grasped the door handle. The smell of dog greeted him. How had a dog gotten here?

John turned the handle and opened the door. A large bloodhound stood before him. The dog was a mess covered in dirt and its hide and muzzle were stained with blood; some of it old and some fresh. It held up its swollen right paw. It limped over to him and caught the sleeve of his jumper in its mouth and giving it a tug. "Bollocks," John muttered pulling his arm away looking at the stain left behind a mixture of dirt, blood, and slobber.

The hound turned and slowly began walking away as John stared after it. It paused and turned back to look at him as another pitiful whine broke the silence. John could sense that the animal wanted him to follow. The question was why. The dog was injured and thin. While the small abandoned flat that John was currently squatting in was far from perfect, there was no electricity or running water, John had managed to scavenge some food and it was well insulated and the windows were boarded offering at least some degree of protection from the infected. John bit his debating. It would be dangerous, but his curiosity was peaked and he could not help but admire the dog's determination. "All right, I'm coming." John murmured under his breath. "I hope I don't regret this." John moved to the bathroom pulled on the soiled jacket. He felt his gorge rise at the smell, but swallowed compulsively until the nausea passed. The jacket was caked the remains of dead infected entrails. While it may seem mad to wear it. It was a vector for infection, but John was immune, it could not infect him. It had a very specific purpose. It made him smell dead giving the infected one less sense to track him with. John tucked his browning under his Jacket into the small of his back and warily followed the hound.

They moved quickly through the dark alleys and deserted corners of the once great city. They moved quietly and John was impressed with the dog's instincts. It stayed in shadow and didn't make a sound as it tracked. Perhaps it was trained? Who would train it? John wondered. The Met? John dismissed the thought. Law enforcement had for the most part fled after the quarantines and evacuations while John was still comatose. John had his answer as the dog slipped into another alley and came an abrupt halt. John caught a glimpse of a man on the ground. John didn't even need to examine him to know that he was dying. Too late, it was much to late. John thought bitterly.

John aimed his browning at the man's sweat soaked brow, his damp obsidian curls were plastered to his forehead and stood out in stark contrast to his pallid complexion. Infected, yet not fully feral. The man's teeth chattered as he shivered relentlessly as the fever ravaged his body. He didn't have long. The man's glassy eyes met John's desperately. They were beautiful, an almost otherworldly color consisting of a mixture of pale blue, green and a hint of grey. "Please, help me." The man pleaded in a voice so weak it was barely audible. His chapped lips were so dry they were close to bleeding. He was dangerously dehydrated. Too late, John repeated to himself, there was nothing John could do for this man besides end his suffering before he turned feral. John cocked the gun and took a steadying breath still reluctant to pull the trigger. John had grown used to killing infected, but this was different. There was still humanity in those eyes and it felt wrong.

John inhaled deeply through his nose and paused. The smell, where was the smell? The infected had a scent signature that John could instantly recognize. It was difficult to describe, but unmistakable. John stepped closer and inhaled again still unable to catch the scent. His hopes rose. Immune. The man must be immune. If his body could fight the virus, he would live. John's hopes sank once again as he took in the state of the man's body. The wound on his hand marked the initial point of entry of the virus, but that was the least of John's concern. The right ankle was bent oddly and swollen obviously broken, it was unlikely that the man could bare weight on it let alone walk unassisted. His right elbow was swollen as well. The injuries were consistent with a fall from a considerable height. John's eyes drifted to the gate and back to the man on the ground. Had he been running from the infected? How long had he been here lying helpless?

John looked beyond the obvious, and became even more worried. The stranger was underweight and his complexion was deathly pale. His rapid labored breathing was another ominous sign of distress. John could see the carotid artery bounding against his skin in a rapid irregular beat, the man was likely going into shock. Without treatment, death would be imminent. Frankly, it was a miracle that the man had survived in this state at all. He was defenseless against the infected who were eager to devour anything living. John's eyes moved once again to the bloodhound that had led him here. Its muzzle was stained with blood and there were scratches on its hide, defensive wounds. It had been guarding its master. The decomposing body of the infected lay before them as evidence. The throat had been ripped opened and the neck was bent at an odd angle, clearly broken. John felt his chest tighten with emotion for the hound, such a noble animal, loyal to the end.


	8. Chapter 8

Chapter 8

Trial and Error

Molly

"Bollocks!" Molly hissed in frustration as she looked at another dead subject. She was getting nowhere. She needed a human subject with immunity. Sherlock had dangled a lead and raised her hopes but she had not heard from him in nearly a fortnight. They were running out of time. Even the quarantine could not stop the virus; only slow its spread. A vaccine was their only hope. Molly was a pathologist and she had a background in epidemiology, but despite that she was still hitting a dead end with the vaccine trials. Animals were for the most part immune and therefore useless in trials. She could not in good conscious expose another volunteer to infection without at least a baseline. She needed a control; someone immune. Nearly everyone had fled London and Molly once again questioned her decision to stay.

Nothing was left here but death. Molly could not deny however, that without a viable vaccine, no place would be safe. Even with the quarantine, the virus would adapt and mutate. It could become airborne. Molly shuddered at the thought. If that happened then it would be unstoppable and humanity as they knew it would be truly doomed. This was why she stayed. She reminded herself. It was a noble ideal, yet so difficult. She was alone and her progress was painfully slow. What's more, the isolation was getting to her. She her mind often drifted. Molly had always been a loner and a bit socially awkward, but there was a difference between being a bit lonely and near complete isolation.

Everyone was gone. Bart's had been boarded up and abandoned. The majority of her friends and colleagues had fallen victim to the infected. The few that survived had fled. Molly was still surprised that she had managed to avoid infection for so long. Lestrade was gone along with nearly all of law enforcement. The last human contact that Molly had been Sherlock. He came and went like an apparition, always with a promise of progress. So close, he claimed. He was so close to finding a subject. Molly sighed once again wondering if she was fighting a losing battle. I can't give up. She told herself. She donned her hazmat suit and carefully collected samples from the dead subject. A recently infected volunteer, who had been desperate enough to try an untested vaccine before they turned completely feral. It had only led to another dead end. Molly sighed and put the sample under the microscope trying to figure out where it had gone wrong.


End file.
